1. Field
The present disclosure relates generally to bend-straightening machines for straightening workpieces, and more particularly, to a bend-straightening machine having a vertically movable table for driving the workpiece against a straightening punch.
2. Description of the Related Art
Bend-straightening machines are known in the art. An exemplary bend-straightening machine is described in U.S. Pat. No. 5,839,315, owned by the assignee of the present application. In U.S. Pat. No. 5,839,315, the actuating mechanism of the machine is based upon cam on roller technology, which utilizes a camshaft mounted in a stationary machine table below straightening bases. The actuating mechanism is designed as a bridge which holds a straightening ram in vertical alignment of a workpiece and the bridge can be moved in a vertical plane by means of a drive mechanism coupled to the camshaft. The bridge is spring-mounted on a base plate of the machine to urge the ram to be in constant engagement with the camshaft to ensure precise alignment with the workpiece. Airbags are also employed are a biasing means to urge the ram against the camshaft.
This known bend-straightening machine operates satisfactorily, but has a disadvantage in that the tonnage and stroke capability of the machine are limited by ergonomic considerations when considering the floor-to-workpiece centerline distance. The large ram structure, which consists of a bridge and uprights, has to be moved with each stroke of the machine requiring a relatively large drive mechanism. Also, due to the plurality of springs supporting the bridge, deformation of any of springs will lead to an asymmetrical load on the workpiece. In addition, the workpiece holding fixtures must be mounted on the fixed machine table and utilize a spring to achieve clamping position, resulting in less than perfect repeatability during measurement.
A bend-straightening machine of similar concept is known from U.S. Pat. No. 6,393,890, also owned by the assignee of the present application. In U.S. Pat. No. 6,393,890, the actuating mechanism consists of cam on roller technology which utilizes a camshaft which is mounted to a rigid machine frame above the workpiece centerline as opposed to below the workpiece centerline as disclosed in U.S. Pat. No. 5,839,315. The actuating mechanism is designed as a ram which holds the straightening punch in vertical alignment of the workpiece and the ram can be moved in the vertical plane by means of the actuating mechanism.
The bend-straightening machine of U.S. Pat. No. 6,393,890 also operates satisfactorily, but has certain disadvantages. The overhead cam arrangement requires the drive mechanism to be mounted to the bridge, which is above the workpiece, requiring a significant support structure in large tonnage machines, thereby increasing its cost. Also, a biasing means, e.g., springs or airbags, are required to bias the cam follower of the ram against the cam to maintain mechanical contact between the cam follower and cam. In addition, the workpiece holding fixtures must be mounted on the fixed machine table and utilize a spring to achieve clamping position, resulting in less than perfect repeatability during measurement.
Therefore, a need exists for a bend-straightening machine having a reduced number of components and which does not require a large support structure. Furthermore, a need exists for a bend-straightening machine that will provide repeatable, accurate straightening of a workpiece.